macro            ::= '%' macro_name [ argList ] '%' ;
argList          ::= '{' args '}' ;
args             ::= cheat_args | well_formed_args ;
cheat_args       ::= any string not including the substring '}%' ;
well_formed_args ::= [ default_arg ] ( spaces named_arg )* ;
default_arg      ::= double_quoted_string ;
named_arg        ::= arg_name '=' double_quoted_string ;
macro_name       ::= /[A-Z][A-Z:_0-9]*/ ;
arg_name         ::= /[a-zA-Z0-9_]*/ ;
spaces           ::= /[\n\t ]+/ ;

::=      introduces a production
;        terminates a production
'%'      indicates a literal
|        separates alternatives
[ ... ]  indicates an optional construct
( ... )+ indicates "one or more of"
( ... )* indicates "zero or more of"
/.../    indicates a regular expression